摘要 |
Carbon monoxide in reformate gas is removed by oxidizing reactions in a plurality of catalytic components (4A-4C) disposed in series. Air from air supply valves (6A-6C) is supplied to the catalytic components (4A-4C). The oxidation amount of carbon monoxide in the catalytic components (4A-4C) depends on air supply flow rates of the air supply valves (6A-6C). A controller (7) controls the air supply valves (6A-6C) so that the ratio of the air supply flow rate to an upstream component (4A) with respect to the air supply flow rate to a downstream component (4C) decreases as a flow rate of reformate gas decreases. In this manner, reverse shift reactions generating carbon monoxide as a result of reactions between carbon dioxide and hydrogen contained in the reformate gas can be suppressed in the downstream catalytic component (4C) when the flow rate of reformate gas is low. |